I have suspected this ever since I have owned these things so today I tested them with my portable GPS. The 100 10hp did 7mph, the LGT165 closed side did 6mph, and my big pretty LGT165 open side only did 5mph. I think all that extra power is lost with the hdyro tarnny, the 100 is all gears.You know sometimes you just have test things to see how fast they are. My Ford 600 tops out at 14mph

Gearing is probably different on the tractors. Higher gearing gives you more speed but less pulling power. Sometimes on a hydro the speed control is worn or out of adjustment and won't let the hydro reach top speed. 5mph seems low for that open side. It's not in low range is it?

I wonder if Brian is not on the right track? Tractor Data says the LGT 165 should run 4.8 on the low side of the axle and 7.1 on the high side. Tire Size Circumfrence would have a lot to do with top speed as well.

the slowest one has worn 23/10:50x12 s on it and it was in higj range. I think its big problem is the pan was rust out around the holes for the pedals and I did not get the hole in the rear large enough and I am not getting full range because of it. Will retest it after I correct that. In using these tractors the 100 seems to pull as much with that granny gear as the LGT 165s